Separation of wax



SM5 OOO@ P4 xmozH MSFUEMQ MD Lf) 1 M. HENDERSON E1' AL SEPARATION F WAX Filed March 23, 1952 L NIOC] 9N L-QIA1 IN VEN TORS Lawrence M Henderson, Co'eymow it( Fer/V19,

Hifi/[y C C'ow/es7 JK v I W ATTORNEY Patented Feb. 19, 1935 'v UNITED STATE-'s PATENTTOFFICEj tion of Pennsylvania` Application'March 23,

l 19 Claims.

The present invention relatesto improving the sweatability of wax, andhas particular utilityin the sweating ofI paraiiin--wax-such as crude, slack wax obtained as a cake when wax-bearing oils from petroleum or shale-oil, forrexamplefoils commonly knownl as paraflin distillates,` are subiected to filter pressing., Our invention specifically resides in the addition of acrystalform impressing agent to such waxes .to improve their. sweatability, that is, their sweating qualities. l

In the past, tofwaxeshaving poor sweating qualities, there was sometimesadded another wax,- more or less at random, with thehope that the resulting mixture would,4 sweat. Usually, the wax added. was known to f have good Vsweating prop'- erties. Bywthis practice,- however, substances were introduced into the wax, which in themselves, we havefound, had' no beneficial effect upongthe sweatabilityof the-.poorly rsweating wax,and in fact, in a number ,of instances, actually hindered sweatability. y f

Good sweating properties in a wax requirelthat its crystalline structure be suchas to allowthe oil and low melting wax ,to Yreadilydrain from the higher melting-f waxfwhen 1the Wax composite :is fractionallymelted. We have recognized that the needle crystal structure best" promotes good sweating 4becauseit maintains openfthe interstices which form between thesolid wax crystals on melting; thereby providing passages throughv which the meltedwaxes and oilcan drain from the vsolidwax. Othercrystal forms of wax do not permit this ready draining of liquid from solid, but insteadv seem to occlude thegoil and'melted wax, thereby hindering onpreventing draining fromtakingplace.- j 1 We employ as our crystal form impressing agent a material of high needlel waxcontent and-,prefer to' employ a wax either specially prepared or selected which is madefup of a preponderance'. of.

'needle wax. VThe significance of the term fneedle wax willappear hereinafter:

; We have found as a result of ourresearch that waxes in general may-logically be classied under one'of three headings,y namelyz` Needle Wax, "fMalcrystalline Wax, and ,-Plate Wax, These terms, while they have some relation to,L are not at all synonymous with. the terms needle crystals, malcrystalline crystals,and plate crystals, as commonly employed in theart. Further,- the4 terms iirst mentioned as employed herein, are

not equivalent to thev loose, indefinite meaning often attributed to such terms in common usage; for example, the term Needle Wax" isy often used by others with indifference to or lack of apprecia- 1932, serial No. 600,584 v f (c1. 19e-2o) tion of thedistinction which exists between v.what we have found to be truefNeedleWaxf,and those waxeswhich are merely of ythe needle crystalline form. We have found,for example, that wax may have a needle crystalline form, ,and yet have needleV wax present inamountsfto ,the extent of only from about 10 to about 20 per cent. Y Itis the true KNeedle Wax, as herein set forth, which comprises theressential component of our needle crystal vform impressing agen`t,vvhichl A"in accordance ,with our invention, is addedto poorly sweating waxes `to, improve their sweating'fproperties. "As y'previously stated, `a wax lof good sweatingproperties isone which will crystallize'to substantial .extent in the formof needles. l

Our needle waxes comprise a series" of specific waxes which-can bestflce,'defined by referenceV to the accompanying drawing.. The drawing is a graph, in ;which the-melting points of. the waxes have been plottedagainst, their refractive indices.

Wehaverfound, upon determining the meltingv points and refractive indices respectively rof a large number of our needlewaxes, andplott'ing such coordinates, that all of our needle waxes fall within a relatively well defined areaonthel graph. Where n representsthe refractive index forthe D line at 80"l C., andv T, represents the melting point of the wax in C., we have found that the needle waxes of major interest in connection 4withy vour process, fall on. the graph within the-group of waxes having', a refractive indexgreater than that denoted by :theexpression n=1.390`l.0.0,01'1.` Such of therabove group of waxes whose refractive indices. do notexceed 1.480, more specifically v1.465, p and still more. speciiicallyli, and whose melts Aing points are; greater than25 C;, and more specifically, within the `range of from 25 C. tof75f C., are more Vparticularly those ywhich we prefer to employ as our agents. um p ,c A U Y Our-needle waxes,` each of vwhichrmay be represented by a single pointon the graph, `may be producedby a 'series rof steps involving iractional distillation and fractional crystallization from solvents, as for example, from- `ethylene dichloride.` .l i c Our inventionis notrestricted `to the employ,- ment of waxes which when subjected to fractional distillation and fractional crystallization will result vinthe productionof wax, all of the com,-

ponents of which ycome within vthe preferred area on the graph as above `set forth. We comprehend employing-a wax; whose. needle Awax content t. isv

concentrated by specialnprocedure `,accordingto the teaching of this invention landwhich, conneedle crystal form ,impressing 2 sidered in a broad sense, may be composed of substantial amounts of constituents coming within the prescribed area on the graph, even though minor amounts of impurities may be present.

In our copending application Serial No. 533,486 filed April 28, 1931, we describe a series of waxes and process for their production, We have found that by employing the series of steps as described in such application, a wax is by each step improved in its crystal form impressing properties. We have found that this increase in-potency of crystal form impressing properties is due to the concentration of what We call needle wax. `With the understanding in mind thatit is high needle wax content which we are interested in and with the understanding of how to measure the needle wax content, the exact process of producing these crystal form impressing agents can obviously be modified, any method applicable to the separation of a mixed material into its `several compounds being applicable here, at least to the extent'of producing some concentration of the needle wax component.

We contemplate the use, as our crystal form impressing agent, of any wax whoseY needle wax content has been specially yconcentrated in accordance with the teaching of this invention, or of any wax or wax fraction, which may be'or have been produced according to known processes of wax refining, having a'high needle wax content and preferably having a needle wax content of the order of 80% or upwards, a wax having a needle wax content of substantially 100% being most preferred. Herein, and inthe appended claims a waxwhose needle wax content has been specially concentrated,'in accordance with the teaching of this invention will be known as a specially prepared waxg.v v y Our crystal form impressing agent is made up of waxes or wax mixtures composed primarily of needle waxes that'fall within the area defined on the graph of the drawing. Impurities may be present in substantial amounts, for example, in

` amounts of the order of 20% or more, and still leave the Wax mixture within the scope of our crystal form impressing agent. However, we prefer to employ as pure a needle wax as possible or a mixture of pure needle waxes. j

To determine whether vor not a certain wax or wax-oil mixture will answer; the preferred requirements of our lcrystal form impressing agent, the following method maybe suitably employed. Take a sample of the mixture under question and add thereto four times its volumev of ethylene dichloride at temperatures vofthe order of 70 F. Then cool the mixture to 0f F. and separate the liquid fromthe crystallized wax as by filtration. This provides a substantially oil-free wax. This wax may then have its refractive index and'melting point determined, which values will -determine a point on the graph of-the drawing. If the point'lies to the right of the line determined by the expression n=1.390+0.001T, above referred to, i. e., a .refractivev index for its'melting point, which is greater than that derivable from the said expression for a similar melting point, and the loss by extraction with ethylene dichloride was not greater than substantially v20% by volume of the original wax, the wax or wax oilv mixture from which the sample was taken answers the characterization of our preferred crystal form impressing agent. If, however, the refractive index-melting point coordinate of the oilfree wax is found to fall to the left of the liney on the graph determined, as above, by the expression n=1.390+0.001T, a further test will be necessary to finally determine Whether or not the substantially oil-free wax contains more nonneedle wax than the amount which together with the oil extracted would constitute substantially 20% of the wax or wax-oil mixture in question. This further test, if desired, may take the form of a fractional distillation by which the wax is I divided into a number of close fractions. If the fractions having melting point refractive index coordinates coming within the range of our described needle Wax, as shown by the graph, equal substantially of the original wax or wax-oil mixture in question, such a wax is still within thecontemplation of our preferred crystal form impressing agent. In making the above measurements of melting point and refractive index it is essential that the wax be a de-oiled Wax, for oil has the tendency to raise the refractive index and certain oil-wax mixtures can be found having melting point refractive index properties coming within the prescribedV area of our needle waxes which are low or entirely lacking in needle wax content.

However, anywax Whose needle wax content has been specially concentrated is within our contemplation as a crystal form impressing agent irrespective of Whether or not its needle Waxy content is above or below 80%. 80 is arbitrarily chosen as the point below which the needle the graph which for practical purposes may be Y;

considered as separating the range of needle wax as defined by us, from other waxes; and these needle waxes We have found have an extraordinarily powerful influence in impressing a needle crystalline form on'Y other waxes of non-needle crystalline form; for example, on waxes of the plate type. By way of illustration,vby taking a needle wax, for example, of 35 C. melting point, and a refractive index ofvl;440, and mixing it with four times its amount of a. plate wax of 45 C. melting point and a refractive index of 1.435, we have found vthat the whole mixture will crystallize in the needle form; and as a matter of fact, the mixture may even form better' needle crystals than the original needle wax itself. However, if this needle crystalline mixture of needle wax and plate wax is now added to four times its amountl of plate wax of 45. Ci., melting point, having a refractive'index of 1.435, We have found that the mixture added does not have the form impressing power'of the original needle wax, in that the resultant mixture will not formr intocrystals of the needle type.l As a further illustration, we admixed with'a needle wax of 45 C. melting point, having a refractive index of 1.444, four times its amount of a plate wax having a melting point of 45 C.,fand a refractive index of 1.434, and found, upon cooling, that the mixture would crystallize into needle crystalline form. For comparison with the previous example,`this needle crystalline Wax mixture, was mixed with four times its amount of a plate wax having a melting point of 45 C., and a refractive index of 1.434, and the resultant wax did not form needle crystals.

' Thus it may readily be seen that it is not the wax mixture ofadequatetainounts of particular waxes, herein called needle waxes. thatcauses an Iinherently nonneedle waxtocrystallize as needles. Our. process,l for improving` the sweating' properties of -a poorly sweating wax bytheaddition of a wax composed Aessentially of needle @wax as herein described, maybe characterized` as one in which aconditioning agent is added. tothe poorly sweating wax. Our processl providesfor substantially excluding .what we have `found to be fthe non-essential or deleteriousl substances and for adding what we vhavefound to constitute the essential crystal form impressing wax components. Hence, 'the sweating properties .of a` wax may befimproved. according to our invention withoutincreasing the volume of the waxtoany considerable extent, whereas by proceeding, according to prior practice, it'may be, and often is, necessaryto addfto a poorly sweating wax two or three times its amount of a good sweating wax in order to so condition the poorly sweating wax that itr will correctlyv sweat.

The needle waxru'sed in our process may bel permitted to remain in vthe final sweated product, .or may beL separated and reusedl as'desired. A convenient ,methodA for separating is by fractional,

distillation, since needle waxes of a given melting point have an appreciably higherboiling point than plate waxes of such melting point. Separa-l. tion ofthe needle wax lfrom the wax to which'it wasadded, in accordance with our invention, may be illustratedby. the following example, in which thesweated wax product is madeup of a representative slack Waxand .a small amount `of a needle wax', the needle wax having a melting point of '55 C., and a refractive. index atv80 C. of 1.475, and a short'boiling range, 50% thereof boiling off'atbr 'above 360 C.,.under an absolute pressure of mm. of mercury; the slack wax has a boiling range of from approximately ,115 C. to 300 C.' From the dilferences in boiling ranges between the needle wax and the wax from which it is to be separated, a substantially complete separation can be made by distillation, the needle wax being left as a residuum. e

When the boiling ranges of the needle wax and the other wax overlap so as to render separation by distillation diflicult orrnon-feasible, the rmethod of solution and fractional recrystallization of the sweated wax from ethylene dichloride or other organic solvent may be employed as a means of separation, with or without the subsequent-step of vacuum distillation.

In the appended claims, where the term needle wax is used, it is to be understood that such term refers to needle wax as hereinabove set forth, as distinguished from mere needle crystals or needle crystalline wax. Also, the expression wax composed substantially of needle wax, in the appended claims is to be understood to comprehend all mixtures of wax composed of preponderating amounts of needle waxes as herein set forth, which may be used to advantage to improve the sweating properties of a poorly sweating wax. Furthermore, when in the appended claims, the

expression improving the sweatability of a wax. is employed, such term is to be understood tov mean either imparting sweatability to a nonsweatable wax or improving the sweating qualities of a wax which to some extent prior thereto was capable of having oil removed therefrom by customary sweating processes.

We claim:

1. A method for improving the sweatability of a wax which comprises adding to the wax aspeciallyy prepared wax having a 'high concentration offneedle wax.` :i w 1 l r 2. Afmethod'for improvingA the sweatability of a wax whichcomprises radding to the: wax a second waxlcomposedpredominantlyof needle wax.

. 3.1-A method.for'improvingjthe sweatability of Va wax which comprises adding tothe wax a specially prepared Wax needle wax.

4. Amethodfor improving the sweatability of afwax which comprises adding to the waxy a seccomposed predominantly of ond wax whichis composedofsat-least substan- 6'. AA method for improving the sweatabilityof a wax rwhich comprises addingto the wax a second wax whichis composed ofat least substantially 80% of needle wax, said needle wax having a melting pointsubstantially as greatas `lthat-of the waxto which itis added. ,Y i

, "7. `A method for improving the sweatability ,cfa

wax-which comprises adding to the wax a second wax whichis composed, of at least substantially 80% Iof needle`waxv,said needlev wax having a melting point greater than-that of the wax to which-it Vis added. 1 c f Egt; Y l l Ind a process for improvinggthesweatability of a poorly'l sweating wax, that improvement which comprises addingitothewax inthe liquid state a wax composed ofa preponderatingpropor-f tion of needlewax e .jy

9. In a process for producing a higher melting wax from a wax mixture, the conditioning step which comprises mixing with the wax a small amount of a wax composed of a preponderating proportion of needle wax. d

10. In a process for improving the sweatability of a hydrocarbon wax, the conditioning step which comprises adding to the wax a second wax composed of a preponderating proportion of constituents having a melting point above C., and a refractive index measured at 80 C., greater than that derived from the expression 11. In a process for improving the sweatability of a hydrocarbon wax, the conditioning step which comprises adding to the wax a second wax composed of a preponderating proportion of wax components having a melting point above 25 C.,

andv a refractive index measured at 80 C., less than 1.480 and greater than that derived from the expression n=1.390+0.001T, where n denotes the value of the refractive index and T denotes the melting point of the wax in C.

12. In a process for improving the sweatability of a hydrocarbon wax, the conditioning step which comprises adding to the wax a second wax `composed of a preponderating proportion of wax components having a melting point above 25 C.,

and a refractive index less than 1.465 and greater than that derived from the expression f where n denotes the value ofthe refractive index, and T denotes the melting point of the wax in A C.

13; In a process for improving the Ysweatability of a hydro-carbon wax, the conditioning step which comprises adding .toisaid'wax a second wax composed of a preponderating proportion :of wax components having amelting point above C. and a refractive index less than 1.445 and'greater than that derived from,` the expression 1 where nl denotes' the value of the refractive index, and T denotes the melting 'point `of the wax in C. v14. In a'process ofsweating a. wax,-those steps which comprise adding to .the .wax'a small amount of a wax composed predominantly of needle wax, subjecting the, waxmixture so produced to the sweating operation, and. removing the needle wax therefrom. '1 i 15. In a process of sweating a wax, those steps which comprise addingtothe wax a small amount of a wax composedV predominantly of components having amelting point A.above`25 "C. and having a refractive index f measured at 80 C. greater than that derived -from the expression n"=1`.390-i-0.001T, y where n denotes the value of the refractive index and T denotes the melting point of the wax' inv C.; subjecting the -wax mixture so produced to the sweating operation; and dissolving and fractionally recrystallizing the sweated, composite wax with an'organic solventfthereby eecting a separation of `needle wax from the'sweated wax.l

16. In a process of sweating a wax, those steps Which-comprise adding to the wax a small amount of a wax composed predominantly of components having a melting point abovev 25 C; and having a refractive indexA measured at 80' C. greater than thatderived from the expression` where n denotes the value ofthe refractive index and T Adenotes the melting point of the wax in CL; subjecting the Waxmixture soproduced to thek sweating operation; and dissolving and fractionally recrystallizing the sweated,' composite wax with ethylenefdichloride, `.thereby eiecting a separation of needle wax from the sweated wax.

17'; In a process of sweating wax those steps which comprise adding to the wax a small amount of a Wax composed predominantly of needle wax; subjecting the wax mixture so' produced to the sweatingoperation; andnsubjecting the sweated, composite wax to a fractional distillation; thereby to eiect a separation of needle wax from the sweated wax,V l

18. In a process of sweating Wax those steps which comprise adding tothe wax a small amount of a wax composed'predominantly'of needle Wax; subjectingv the wax mixture so produced to the sweating operation; and subjecting the sweated, composite wax to a fractional distillation under vacuum,-thereby to effect a separationl of needle wax from ythe sWeated-wax. 19. Iny a process forV sweating Wax those steps which comprise add'ingto the wax a small amount of a wax composed predominantly of needle wax, subjecting `the wax mixtures vso produced to a 'sweating operation, subjecting the sweated, composite waxto `fractional distillation, thereby to effect a separation of the Aneedle wax added from the wax mixture, thereafter adding suchv needle wax to wax to be sweated, and subjecting the wax mixture so produced to asweating operation.

LAWRENCE M. HENDERSON. SEYMOUR W. EERRIs. vHENRY C. coWLEs,` JR. 

